Impulse signal transmission system



J y 7- c. DE-VRIENDT EEMPULSE SIGNAL TRANSMISSION SYSTEM Filed Marh 24,1945 INVENTOR Can: 42s 1: Vex/m7- ATTORNEY Patented July 1, 1947 IMPULSESIGNAL TRANSMISSION SYSTEM Charles De Vriendt, Antwerp, Belgium,assignor to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Application March 24, 1943, Serial No.480,418 In the Netherlands June 21, 1941 The present invention relatesto improvements in signal transmission systems in general and hasreference in particular to impulse transmission systems.

It is common practice to incorporate in telephone systems, or similarsystems for establishing connections, improvements or additionalfacilities for the service. These require an additional signalizationeither between different switching stages in the same exchange, orbetween different exchanges in the same area or in different areas.

One of the main difiiculties encountered in this connection resides inthe fact that it is necessary to provide new signalling paths, becausethe existing conductors of the junctions between switching stages orbetween exchange are usually not available for this purpose.

The principal object of the invention is to pro vide a signalling systemfor impulse transmission which utilizes an existing conductor withoutinterrupting or interfering with the purposes for which this conductoris normally used. In brief, I accomplish this and other objects of theinvention, as will become more apparent hereinafter, by providing forcontinuous transmission of an alternating current over the signallingwire during each complete train of impulses. According to anotherfeature of the invention, synchronized stepping mechanisms are providedat the sending as well a at the receiving end. According to a furtherfeature of the invention, a cold-cathode tube is used at the receivingend as relay control means, whereby the signalling system according tothis invention may be operated with a minimum of energy.

An embodiment of the present invention is illustrated, by way ofexample, in the accompanying drawing.

In the drawing, numerals I, 2 represent any kind of connecting wirehaving a certain impedance X. Same consists of any combination ofresistances, capacities and inductances. Normally, this wire is used forsignalling purposes on a direct current or alternating currentbasis.

Condensers C1 and C2 serve to separate any existing direct currentsignals from the signalling system according to the invention.Condensers C1, C2 in conjunction with impedance X and primary winding pof transformer T are tuned to resonance with frequency 1, which usuallycomes within the voice frequency range employed in the signalling systemaccording to the invention. 7

Letters SS designate the power magnet of a step-by-step selector switchof well known type,

20 Claims. (01. 179-16) for instance such as are used in telephone orlike systems for establishing connections. The two terminal banks a andb are shown with their respective brush members a1 and b1.

Switch SS serves two purposes, viz.: (l) for connecting a continuousalternating current of frequency f to thesignalling wire via level a;and (2) for disconnecting said alternating current via level 1), whenthe complete train of impulses which corresponds to a particular signal,is terminated.

Relays B1, B2, B3 and B4 perform various functions, as will be explainedhereafter.

The cold-cathode tube L, used according to the invention, is of wellknown type, requiring a specific control gap between potential Vx toignite the control gap between the two electrodes c1 and 62, while asubstantially higher main gap breakdown potential Vy is needed forigniting the main gap between the anode A and either one of the twoelectrodes 61 and ez. Once the control gap has been ignited however, asustaining potential Vz, which may be considerably lower than Vy,suffices to maintain a current across the main gap.

As shown in the drawing, secondary winding 8 of transformer T isinserted between a connecting point on potentiometer P and control anodec1 of cold cathode tube L, while anode A is connected in series withrelay B4. The latter reproduces the impulses produced at the sendingstation. The anode circuit can be closed only by the control action ofrelay B3, whose armature steps in synchronism with stepping relay B1 ofthe sending station. The control relay B2 of the sending stationoperates over a marking wire when a predetermined number of impulses hasbeen transmitted.

Elements IMP1 and IMPz are two mechanical or electrical impulsegenerators. If located in the same exchange, these two generators maycomprise impulse cams mounted on the same shaft. Synchronization is thusobtained without special means. If the two impulse generators arelocated at different exchanges, they may be synchronized by any numberof methods, known per se. These methods will not be further described asnot coming within the scope of the present invention.

Generator IMP1 may be provided for a plurality of circuits and/orexchanges in common, which results in a considerable economy in lineplant.

Starting key Sir is closed when impulse transmission is to be started.Key Sh may be opened again at any convenient time after thesignalization has been completed. Starting contact Sta 3 is closed assoon as the circuit at the receiving end has been seized and is readyfor the reception of impulses.

On the basis of the foregoing explanation of the character and functionof the various devices shown in the drawing, a detailed description ofth operation of the system is given in the following.

Let us assume that the receiving end circuit has been seized and thestarting contact St: is closed. In that event, relay B: will operate insynchronism with the impulses from generator IMPi, but nothing furtherwill happen.

When the sending station is ready to start the transmission of impulses,starting contact Sti is closed. Relay B1 operates as soon as the impulsesender IMPZ grounds for the first time its rotating brush member,causing the energization of power magnet SS. As soon as the groundconnection of generator IMPz is broken, relay Bl releases and thebrushes of the switch complete the first step. At this moment, analternating current of frequency f is sent out over the line to thereceiving end.

At the receiving end, tube L is normally not ignited because the biasingpotential of control anode 61 is such, that the potential differencebetween 61 and (22 is lower than the control gap breakdown voltage.

However, upon receipt of the alternating current from the sending end, acertain potential is induced in the secondary winding of transformer Tand the peak of one half-wave of this potential is then added tothebiasing potential of c1, with the result that the control gap is ignitedand remains ignited as long as the alternating current continues.

The next time when generator IMP2 connects relay B1 to ground, thisrelay is actuated and energizes element SS. Simultaneously, relay B3 isgrounded and hence put in operation. As a result, the anode circuit ofthe tube L is closed. Since th control gap is ignited, the main gap isnow likewise. ignited and relay B4 is operated, closing the localstepping circuit (not shown).

However, as soon as the ground connection of the impulse senders isbroken, relays Bi and B3 release, the brushes of the switch take anotherstep and relay B4 opens its stepping contact. One impulse is thustransmitted in the manner described above.

Each subsequentv impulse is. transmitted in exactly the same manner.

If it is desired to transmit a signal comprising four impulses, forinstance, the following connections are established:

When the ground connection of the impulse senders is broken after relayB4 has closed its stepping contact four times, the brushes of switch SStake a further step and stop on terminal 5.

Relay B4 then becomes de-energized. However,

at the beginning of the operations, the impulse transmission controldevice caused terminal 5, in bank I). of switch SS, to be connected toground, thereby determining that the complete train of impulsesconstituting the signal shall consist ofbut four impulses.

As a result, as soon as the switch, arrives at terminal 5,, relay B2operates via bank I), and the alternating current is cut off from the;line.

Since at this moment the anode circuit of the tube L is opened, thecontrol gap of the same is extinguished and no further impulses can bereceived until the sending circuit. is again, ready to transmit somesubsequent signals- Special attention is directed to the greatadvantages produced by this invention from the point of View ofelectrical interference. While the impulses are being transmitted, theimpedance of the signalling conductor remains unchanged and, when relayB2 operates, this conductor is connected to ground, which, practicallyspeaking, does not alter th impedance, because the impedance of the A.C. generator in itself is very small.

I am aware of the fact that many changes may be made in the signallingsystem according to the present invention without departing from thespirit and scope of the same. I therefore do not wish to be understoodas limiting myself to the exact details of construction and arrangementshown and described herein.

I claim:

1. In a signalling system, a sending station, a receiving station, and atransmitting line interconnecting said stations, first impulse producingmeans associated with said sending station, second impulse producingmeans associated with said receiving station, supply means for supplyingelectric energy to said transmitting line, operative means at saidreceiving station associated with said second impulse producing means,said operative meansbeing adapted to respond only to the combined actionof said second impulse producing means and the electric energy suppliedover said transmitting line, whereby the efiect of said second impulseproducing means may be controlled from said sending station, bysupplying or discontinuing the supply of electric energy at the sendingstation.

2. In a signalling system, a sending station, a receiving station, anda, transmitting line interconnecting said stations, first impulseproducing means associated with said sending station, second impulseproducing means associated with said receiving station, supply means forsupplying electric energy to said transmitting line, control meansassociated with said first impulse producing means and said supplymeans, said control means being adjustable for various numbers ofimpulses representing predetermined signals, and adapted toautomatically disconnect said supply means from said transmitting lineafter delivery by said first impulse producing means of the number' ofthe impulses for which said control means has been adjusted, operativemeans at said receiving station associated with said second impulseproducing means, said operative means being adapted to respond only tothe combined action of said second impulse producing means and theelectric energy supplied over said transmitting line, whereby the effectof said second impulse producing means may be controlled from saidsending station, by supplying or discontinuing the supply of electricenergy at the sending station.

3. In a signalling system, the combination with a sending station, areceiving station, a transmitting line interconnecting said stations, afirst impulse circuit associated with said sending station, firstimpulse producing means in said first impulse circuit, a second impulsecircuit associated with said receiving station, second impulse producingmeans in said second impulse circuit, said first and second impulseproducing means operating synchronouslywitheach other, wherebycorresponding impulses are produced in both said impulse circuits of thesending station and the. receiving station, of control means disposed atthe sending'station and electrically connected with said transmittingline, said control meansceiving station, a second impulse generator insaid second impulse circuit, said impulse generators operatingsynchronously with each other, whereby, upon creation of an impulse orof a group of impulses in the first impulse circuit, a correspondingimpulse or roup of impulses is simultaneously created in said secondimpulse circuit, control means associated with said first impulsecircuit, a source of electric energy associated with said sendingstation and adapted to be connected to said transmitting line by saidcontrol means, the latter being adjustable for a certain number ofimpulses and, adapted to open said first impulse circuit and disconnectsaid source of electric energy from said transmitting line when thenumber of impulses for which it is adjusted, has been delivered;cooperating means at the receiving station associated with said secondimpulse circuit, said cooperating means being electrically connected tosaid transmitting line and adapted to respond only to the combinedaction of said impulses in said second impulse circuit and the energysupplied from said source of electric energy, said impulses in saidsecond impulse circuit being ineffectual when transmission of energyover said transmitting line is discontinued by said control means,whereby only the number of impulses selected at the sending station andconstituting a particular signal, will be delivered at the receivingstation, irrespective of whether or not said second impulse generatorcontinues to create impulses in said second impulse circuit.

5. The system claimed in claim 1, in which said means for supplyingelectric energy is a source of alternating current.

6. The system claimed in claim 1, in which said operative means includesa cathode tube fed by the electric energy supplied over saidtransmitting line.

7. The system claimed in claim 1, in which said means for supplyingelectric energy is a source of alternating current, and said operativemeans includes a cathode tube and a transformerhaving a primary and asecondary, said cathode tube being connected to said secondary, and saidprimary being connected to said transmitting line.

8. The system claimed in claim 4, in which said source of electricenergy is an alternating current source, and said cooperating meanscomprises a transformer having a, primary, same being connected to saidtransmitting line.

9. The system claimed in claim 4, in which said source of electricenergy is an alternating current source, and said cooperating meanscomprises a transformer having a, primary, same being connected to saidtransmitting line, said transformer also comprising a secondary and saidcooperating means including a cathode tube, said secondary beingconnected to said cathode tube.

10. The system claimed in claim 4, in which said control means comprisesa step-by-step selector switch controlled by said first impulse circuit,whereby each impulse causes said switch to advance one step.

11. The system claimed in claim 4, in which said control means comprisesa first step-by-step selector switch controlled by said first impulsecircuit, a second step-by-step selector switch being associated with andcontrolled by said cooperating means, whereby each impulse in saidimpulse circuits causes said switches to advance one step insynchronism, operation of said second switch discontinuing upondisconnection of said source of electric energy from said transmittingline, irrespective of whether or not impulses continue to be created insaid second impulse circuit.

12. The system claimed in claim 4, in which said first impulse circuitincludes a first relay and said control means includes a switch circuit,a step-by-step selector switch in said switch circuit, the latter beingcontrolled by said first relay, whereby each impulse delivered by saidfirst generator is transmitted to said first relay causing saidstep-by-step selector switch to advance one step, a first and secondterminal bank, a first and second contact member associated with saidterminal banks respectively, said contact members being controlled bysaid first step-by-step switch, whereby each step of said first switchcauses each contact member to advance to the next terminal of therespective bank of terminals, the terminals of the first bank beingconnected to said transmitting line, said first contact member beingconnected to said source of electric energy; a control circuit connectedto said second contact member, a second relay in said control circuit,adjusting means adapted to be moved to any desired terminal of saidsecond bank of terminals, said adjusting means being grounded, wherebysaid second relay is energized when said second contact member is movedby said first switch into contact with a terminal grounded by saidadjusting means, said second relay being adapted to disconnect saidsource of electric energy from said transmitting line.

13. The system claimed in claim 4, in which said first impulse circuitincludes a first relay and said control means includes a switch circuit,a step-by-step selector switch in said switch circuit, the latter beingcontrolled by said first relay, whereby each impulse delivered by saidfirst generator is transmitted to said first relay causing saidstep-by-ste-p selector switch to advance one step, a first and secondterminal bank, a first and second contact member associated with saidterminal banks respectively, said contact members being controlled bysaid first step-by-step switch, whereby each step of said first switchcauses each contact member to advance to the next terminal of therespective bank of terminals, the terminals of the first bank being connected to said transmitting line, said first contact member beingconnected to said source of electric energy; a control circuit connectedto said second contact member, a second relay in said control circuit,adjusting means adapted to be moved to any desired terminal of saidsecond bank of terminals, said adjusting means being grounded, wherebysaid second relay is energized when said second contact member is movedby said first switch into contact with a terminal grounded by saidadjusting means, said second relay being adapted to disconnect saidsource of electric energy from said transmitting line, and being furtheradapted to simultaneously break said first impulse circuit. v

14. The system claimed in claim 4, in which said cooperating meansincludes a cathode tube 7 comprising a pair of electrodes and an anode,a tube circuit, said electrodes being disposed in saidt'ube circuit, ananode'circult for said anode,

said anode circuit being grounded, a first relay, the latter beingdisposed in said second impulse circuit, said first relay being adaptedto open and close said anode circuit, a second relay, same beingdisposed in said anode circuit and adapted to control a step by-stepswitch circuit.

5. The system claimed in claim 4', in which said cooperating meansincludes a cathode tube comprising a pair of electrodes and an anode, atube circuit, said electrodes being disposed in said tube circuit, ananode circuit for said anode, said anode circuit being grounded, a firstrelay, the latter being disposed in said second impulse circuit, saidfirst relay being adapted to open and close said anode circuit, a secondrelay, same being disposed in said anode circuit and adapted to controla step-by-step switch circuit; a transformer having a primary and asecondary, said secondary being disposed in said tube circuit and saidprimary being connected to said transmitting line.

16. The system claimed in claim 4, in which said cooperating meansincludes a cathode tube comprising a pair of electrodes and an anode, atube circuit, said electrodes being disposed in :said' tube circuit, ananode circuit for said anode, said anode circuit being grounded, a firstrelay, the latter being disposed in said second impulse circuit, saidfirst relay being adapted to open and close said anode circuit, a secondrelay, same being disposed in said anode circuit and adapted to controla step-by-step switch circuit, a second source of electric energy, samebeing disposed in said tube circuit and feeding said tube.

17. The system claimed in claim 4, in which said cooperating meansincludes a cathode tube comprising a pair of electrodes and an anode, atube circuit, said electrodes being disposed in 'said tube circuit, ananode circuit for said anode, :said anode circuit being grounded, afirst relay, the latter being disposed in said second impulse circuit,said first relay being adapted to open and close said anode circuit, asecond relay, same being disposed in said anode circuit and adapted 'tocontrol a step-by-step switch circuit, a second source of electricenergy, same being disposed in said tube circuit and feeding said tube,and a potentiometer associated with said tube circuit and said secondsource of electric energy, whereby the voltage supplied to said tube bysaid second source of electric energy may be varied.

13. The system claimed in claim 4, in which :said cooperating meansincludes a cathode tube comprising a pair of electrodes and an anode, atube circuit, said electrodes being disposed in said tube circuit, ananode circuit for said anode, said anode circuit being grounded, a firstrelay, the latter being disposed in said second impulse circuit, saidfirst relay being adapted to open and close said anode circuit, a secondrelay, same bein disposed in said anode circuit and adapted to control astep-bystep switch circuit, said pair of electrodes being spaced apartto form a control gap, a main gap being formed by said anode and saidelectrodes, the breakdown potential for ignitin said control gap beinglower than the breakdown potential of said main gap, the breakdownpotentials beingso chosen that the sustain- .ing potential required tomaintain the current acros the main gap, once the same has been 8ignited; is lower than the main gap breakdown potential. v

19. The system claimed in claim 4, in which said first impulse circuitincludes a first relay and said control means includes a switch circuit,a step-by-step selector switch in said switch circuit, the latter beingcontrolled by said first relay, whereby each impulse delivered by saidfirst generator is transmitted to said first relay causing saidstep-by-step selector switch to advance one step, a first and secondterminal bank, a first and second contact member associated with saidterminal banksrespectively, said contact members being controlled bysaid first stepby-step switch, whereby each step of said first switchcauses each contact member to advance to the next terminal of therespective bank of terminals, the terminals of the first bank beingconnected to said transmittin line, said first contact member beingconnected to said source of electric energy; a control circuit connectedto said second contact member, a second relay in said control circuit,adjusting means adapted to be moved to any desired terminal of saidsecond bank of terminals, said adjusting means being grounded, wherebysaid second relay is energized when said second contact member is movedby said first switch into contact with a terminal grounded by saidadjusting means, said second relay being adapted to disconnect saidsource of electric energy from said transmitting line; said cooperatingmeans including a cathod tube having a pair of electrodes and an anode,a tube circuit, said electrodes being disposed in said tube circuit, ananode circuit for said anode, said anode circuit being grounded; a thirdrelay, the latter being disposed in said second impulse circuit, saidthird relay being adapted to open and close said anode circuit, a fourthrelay, same being disposed in said anode circuit and adapted to controla step-by-step switch circuit; a transformer having a primary and asecondary, said secondary being disposed in said tube circuit and saidprimary being connected to said transmitting line; a second source ofelectric energy, same being disposed in said tube circuit and feedingsaid tube, and a potentiometer associated with said tube circuit andsaid second source of electric energy, whereby the voltage supplied tosaid tube by said second source of electric energy may be varied; saidpair of electrodes bein spaced apart to form a control gap, ,9, main gapbeing formed by said anode and said electrodes, the breakdown potentialfo igniting said control gap being lower than the breakdown potential ofsaid main gap, the breakdown potentials being so chosen that thesustaining potential required to maintain the current across the maingap, once the same has been ignited, is lower than the main gapbreakdown potential.

20. The system claimed in claim 4, in which said first impulse circuitincludes a first relay and said control means includes a switch circuit,a step by-step selector switch in said switch cir cuit, the latter beingcontrolled by said first relay, whereby each impulse delivered by saidfirst generator is transmitted to said first relay causing saidstep-by-step selector switch to advance one step, a first and secondterminal bank, a first and second contact member associated with saidterminal banks respectively, said contact members being controlled bysaid first step-by-step switch, whereby each step of said first switchcauses each contact member to advance to the next terminal of therespective bank of terminals,

9 the terminals of the first bank being connected to said transmittingline, said first contact member being connected to said source ofelectric energy; a control circuit connected to said second contactmember. a second relay in said control circuit, adjusting means adaptedto be moved to any desired terminal of said second bank of terminals,said adjusting means being grounded, whereby said second relay isenergized when said second contact member is moved by said first switchinto contact with a terminal grounded by said adjusting means, saidsecond relay being adapted to disconnect said source of electric energyfrom said transmitting line; said cooperating means including a cathodetube having a pair of electrodes and an anode, a tube circuit, saidelectrodes being disposed in said tube circuit, an anode circuit forsaid anode, said anode circuit being grounded; a third relay, the latterbeing disposed in said second impulse circuit, said third relay beingadapted to open and close said anode circuit, a fourth relay, same beingdisposed in said anode circuit and adapted to control a stepby-stepswitch circuit; a transformer having a primary and a secondary, saidsecondary being disposed in said tube circuit and said primary 10 beingconnected to said transmitting line; a second source of electric energy,same being disposed in said tube circuit and feeding said tube, and apotentiometer associated with said tube circuit and said second sourceof electric energy, whereby the voltage supplied to said tube by saidsecond source of electric energy may be varied; said pair of electrodesbeing spaced apart to form a control gap, a main gap being formed bysaid anode and said electrodes, the breakdown potential for ignitingsaid control gap being lower than the breakdown potential of said maingap, the breakdown potentials being so chosen that the sustainingpotential required to maintain the current across the main gap, once thesame has been ignited, is lower than the main gap breakdown potential; apair of condensers in said transmitting line, one condenser beingdisposed at the sending station and the other condenser being disposedat the receiving station, said condensers serving to filter out anydirect current signals in the transmitting line; and a starting keydisposed in each of said first and second impulse circuits forcontrolling the operation thereof.

CHARLES DE VRIENDT.

